After wells have been drilled and placed in production and, in some cases, during drilling operations, it is necessary to conduct electric logs and/or perform downhole servicing of well equipment. In many cases, the downhole equipment is designed for servicing by means of various tools which are lowered into the well on a wireline. Wireline servicing is a significantly inexpensive servicing operation as compared to the cost of removing production tubing and equipment from the well for servicing.
Wireline servicing operations are performed inside oil and gas wells while the wells are maintained under pressure. The cable and tools are introduced into the pressurized well, using well known wireline pressure control equipment and techniques. One necessary part of wireline servicing equipment is a wireline control valve which is also referred to as a blowout preventer. The wireline control valve is used to center the wireline cable and seal around the motionless wireline cable to allow the upper parts of the control equipment to be depressurized and removed for repair of the wireline or control equipment. For example, a strand of cable armor can break and jam inside the pressure control lubricator pipe, preventing the cable from being withdrawn from the well. To make repairs, the wireline valve is closed around the cable to form a seal and the pressure above the wireline valve is vented. The union above the wireline valve is then unscrewed and the lubricator is raised and the cable is clamped to keep it from falling downhole. After this has been accomplished, the repair work can begin. This repair work must be done by workers working directly over the wireline valve opening, or very nearby. In the event the wireline valve should begin to leak around the cable after the union has been unscrewed, the safety of the workers will be in serious jeopardy. It is a matter of record that it is difficult to obtain and maintain a seal around the armored type, wireline cable, since well fluids can migrate between the inner and outer layers of the cable armor. There is, therefore, a need for an auxiliary cable seal, means for diverting leaking fluids to a safe location, and means for clamping the cable. Moreover, it is necessary that the wireline servicing device be capable of installation without necessitating cutting of the cable.